linux/drivers/hid/hid-primax.c
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   1/*
   2 * HID driver for primax and similar keyboards with in-band modifiers
   3 *
   4 * Copyright 2011 Google Inc. All Rights Reserved
   5 *
   6 * Author:
   7 *      Terry Lambert <tlambert@google.com>
   8 *
   9 * This software is licensed under the terms of the GNU General Public
  10 * License version 2, as published by the Free Software Foundation, and
  11 * may be copied, distributed, and modified under those terms.
  12 *
  13 * This program is distributed in the hope that it will be useful,
  14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 * GNU General Public License for more details.
  17 */
  18
  19#include <linux/device.h>
  20#include <linux/hid.h>
  21#include <linux/module.h>
  22
  23#include "hid-ids.h"
  24
  25static int px_raw_event(struct hid_device *hid, struct hid_report *report,
  26         u8 *data, int size)
  27{
  28        int idx = size;
  29
  30        switch (report->id) {
  31        case 0:         /* keyboard input */
  32                /*
  33                 * Convert in-band modifier key values into out of band
  34                 * modifier bits and pull the key strokes from the report.
  35                 * Thus a report data set which looked like:
  36                 *
  37                 * [00][00][E0][30][00][00][00][00]
  38                 * (no modifier bits + "Left Shift" key + "1" key)
  39                 *
  40                 * Would be converted to:
  41                 *
  42                 * [01][00][00][30][00][00][00][00]
  43                 * (Left Shift modifier bit + "1" key)
  44                 *
  45                 * As long as it's in the size range, the upper level
  46                 * drivers don't particularly care if there are in-band
  47                 * 0-valued keys, so they don't stop parsing.
  48                 */
  49                while (--idx > 1) {
  50                        if (data[idx] < 0xE0 || data[idx] > 0xE7)
  51                                continue;
  52                        data[0] |= (1 << (data[idx] - 0xE0));
  53                        data[idx] = 0;
  54                }
  55                hid_report_raw_event(hid, HID_INPUT_REPORT, data, size, 0);
  56                return 1;
  57
  58        default:        /* unknown report */
  59                /* Unknown report type; pass upstream */
  60                hid_info(hid, "unknown report type %d\n", report->id);
  61                break;
  62        }
  63
  64        return 0;
  65}
  66
  67static const struct hid_device_id px_devices[] = {
  68        { HID_USB_DEVICE(USB_VENDOR_ID_PRIMAX, USB_DEVICE_ID_PRIMAX_KEYBOARD) },
  69        { }
  70};
  71MODULE_DEVICE_TABLE(hid, px_devices);
  72
  73static struct hid_driver px_driver = {
  74        .name = "primax",
  75        .id_table = px_devices,
  76        .raw_event = px_raw_event,
  77};
  78
  79static int __init px_init(void)
  80{
  81        return hid_register_driver(&px_driver);
  82}
  83
  84static void __exit px_exit(void)
  85{
  86        hid_unregister_driver(&px_driver);
  87}
  88
  89module_init(px_init);
  90module_exit(px_exit);
  91MODULE_AUTHOR("Terry Lambert <tlambert@google.com>");
  92MODULE_LICENSE("GPL");
  93
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